使用Kryo序列化任意Java对象（获取IllegalAccessError）

Z时代
2024-01-10
分类：问答

回答：

为了帮助进行远程调试（Java），能够请求远程服务器将任意对象发送到我的本地计算机进行检查是很有用的。但是，这意味着远程服务器必须能够序列化运行时事先未知的任意Java对象。

于是我四处询问，偶然发现了Kryo序列化库。根据Kryo的文档，主要功能是在序列化任意Java对象方面非常强大。对象不必实现Serializable，不需要no-

arg构造函数就可以反序列化，而且我甚至不需要在序列化之前就了解对象的结构。完善！

回答：

因此，为了测试Kryo，我尝试查看是否可以序列化然后反序列化一个PrintWriter对象（即任意对象）：

import com.esotericsoftware.kryo.Kryo;
import com.esotericsoftware.kryo.io.Input;
import com.esotericsoftware.kryo.io.Output;
import java.io.*;
public class SerializationTest {
    private static final String ioFileName = "someIO.bin";
    public static void main(String[] args) {
        // Create a PrintWriter object that I will later attempt to serialize
        PrintWriter outObj = null;
        try {
            outObj = new PrintWriter("textfile.txt");
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        // Change the PrintWriter's state as a test for later to see if state is restored after serialization and deserialization
        outObj.println("Hello");   // "Hello" held in PrintWriter's buffer
        Kryo kryo = new Kryo();    // Initialize Kryo serialization
        writeObj(kryo, outObj);    // Save PrintWriter object to file with "Hello" still in its buffer
        // Read the previously saved Printwriter object (still with "Hello" in its buffer)
        PrintWriter inObj = (PrintWriter) readObj(kryo);
        inObj.close();    // commit "Hello" to disk (using deserialized object)
        outObj.close();   // commit "Hello" to disk (using original object)
        System.out.println(inObj);
    }
    public static Object readObj(Kryo kryo) {
        Object obj = null;
        try {
            Input input = new Input(new FileInputStream(ioFileName));
            obj = kryo.readClassAndObject(input);   // ERROR HERE!!
            input.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        return obj;
    }
    public static void writeObj(Kryo kryo, Object obj) {
        try {
            Output output = new Output(new FileOutputStream(ioFileName));
            kryo.writeClassAndObject(output, obj);
            output.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }
}

序列化工作正常，但是反序列化后，kryo.readClassAndObject(input)对第39行的调用给出了以下内容IllegalAccessError：

Exception in thread "main" java.lang.IllegalAccessError: tried to access class sun.nio.cs.UTF_8 from class sun.nio.cs.UTF_8ConstructorAccess
    at sun.nio.cs.UTF_8ConstructorAccess.newInstance(Unknown Source)
    at com.esotericsoftware.kryo.Kryo$DefaultInstantiatorStrategy$1.newInstance(Kryo.java:1234)
    at com.esotericsoftware.kryo.Kryo.newInstance(Kryo.java:1086)
    at com.esotericsoftware.kryo.serializers.FieldSerializer.create(FieldSerializer.java:547)
    at com.esotericsoftware.kryo.serializers.FieldSerializer.read(FieldSerializer.java:523)
    at com.esotericsoftware.kryo.Kryo.readObject(Kryo.java:704)
    at com.esotericsoftware.kryo.serializers.ObjectField.read(ObjectField.java:106)
    at com.esotericsoftware.kryo.serializers.FieldSerializer.read(FieldSerializer.java:528)
    at com.esotericsoftware.kryo.Kryo.readObject(Kryo.java:704)
    at com.esotericsoftware.kryo.serializers.ObjectField.read(ObjectField.java:106)
    at com.esotericsoftware.kryo.serializers.FieldSerializer.read(FieldSerializer.java:528)
    at com.esotericsoftware.kryo.Kryo.readObject(Kryo.java:704)
    at com.esotericsoftware.kryo.serializers.ObjectField.read(ObjectField.java:106)
    at com.esotericsoftware.kryo.serializers.FieldSerializer.read(FieldSerializer.java:528)
    at com.esotericsoftware.kryo.Kryo.readObject(Kryo.java:704)
    at com.esotericsoftware.kryo.serializers.ObjectField.read(ObjectField.java:106)
    at com.esotericsoftware.kryo.serializers.FieldSerializer.read(FieldSerializer.java:528)
    at com.esotericsoftware.kryo.Kryo.readClassAndObject(Kryo.java:786)
    at SerializationTest.readObj(SerializationTest.java:39)
    at SerializationTest.main(SerializationTest.java:27)